题解 | #提取不重复的整数#

#include <iostream>
#include <string>
#include <algorithm>
#include <unordered_set>

using namespace std;

int main(){
    int num = 0;
    cin >> num;
    
    string str = to_string(num);
    reverse(str.begin(), str.end());
    unordered_set<char> tmp;
    int res = 0;
    
    for(int i = 0; i < str.size(); i++){
        if(tmp.count(str[i]) == 0){
            res = res * 10 + (str[i] - '0');
        }
        tmp.insert(str[i]);      
    }
    
    cout << res << endl;
    
    return 0;
}